Optical imaging system

ABSTRACT

An optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens sequentially disposed on an optical axis from an object side toward an image side. A distance from an object-side surface of the first lens to an imaging plane of an image sensor is TTL, an overall focal length of an optical system including the first to sixth lenses is F, and TTL/F≤0.83. An optical axis distance between the second lens and the third lens is D23, an optical axis distance between the third lens and the fourth lens is D34, and 2.2&lt;D23/D34&lt;5.4.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 USC 119(a) of Korean PatentApplication No. 10-2017-0141370 filed on Oct. 27, 2017, in the KoreanIntellectual Property Office, the entire disclosure of which isincorporated herein by reference for all purposes.

BACKGROUND 1. Field

This application relates to an optical imaging system.

2. Description of the Background

Recently, mobile communications terminals have been provided with cameramodules, enabling video calling and image capturing. As the utilizationof camera modules mounted in mobile communications terminals hasincreased, camera modules for mobile communications terminals havegradually been required to have higher resolution and performance.

Because there is also a trend to gradually miniaturize and lightenmobile communications terminals, there may be limitations in realizingcamera modules having high resolution and performance.

In addition, a telephoto lens has a relatively long focal length.Accordingly, a total length (TTL) thereof may be increased, which maymake it difficult to mount such a telephoto lens in a small portableelectronic device.

The above information is presented as background information only toassist with an understanding of the present disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

In one general aspect, an optical imaging system includes a first lens,a second lens, a third lens, a fourth lens, a fifth lens, and a sixthlens sequentially disposed on an optical axis from an object side towardan image side. A distance from an object-side surface of the first lensto an imaging plane of an image sensor is TTL, an overall focal lengthof an optical system including the first to sixth lenses is F, and TTL/Fis less than or equal to 0.83. An optical axis distance between thesecond lens and the third lens is D23, an optical axis distance betweenthe third lens and the fourth lens is D34, and D23/D34 is greater than2.2 and less than 5.4.

A field of view of the optical system including the first to sixthlenses is FOV and FOV may be less than or equal to 44°.

A focal length of the first lens is f1 and f1/F may be greater than 0.3and less than 0.4.

An optical axis distance between the first lens and the second lens isD12 and D23/D12 may be greater than 10 and less than 22.

An optical axis distance between the fourth lens and the fifth lens isD45, an optical axis distance between the fifth lens and the sixth lensis D56, and D45/D56 may be greater than 58 and less than 65.

The first lens may have positive refractive power, and among absolutevalues of focal lengths of the first to sixth lenses, the absolute valueof the focal length of the first lens may be the shortest.

The second lens may have negative refractive power and an image-sidesurface thereof may be concave.

The third lens may have negative refractive power, an object-sidesurface thereof may be convex, and an image-side surface thereof may beconcave.

The fourth lens may have positive or negative refractive power, anobject-side surface thereof may be convex, and an image-side surfacethereof may be concave.

The fifth lens may have negative refractive power, an object-sidesurface thereof may be concave, and an image-side surface thereof may beconvex.

The sixth lens may have positive refractive power, an object-sidesurface thereof may be concave, and an image-side surface thereof may beconvex.

The first to sixth lenses may each be formed of plastic comprisingoptical characteristics different from an adjacent lens.

A stop may be disposed between the third lens and the fourth lens.

At least one inflection point may be formed on an object-side surface ofthe fourth lens.

In another general aspect, a multi-member optical imaging systemincludes a first optical imaging system having a first field of view anda second optical imaging system having a second field of view differentfrom the first field of view. The first optical imaging system includesa first lens, a second lens, a third lens, a fourth lens, a fifth lens,and a sixth lens sequentially disposed on an optical axis from an objectside toward an image side. A distance from an object-side surface of thefirst lens to an imaging plane of an image sensor is TTL, an overallfocal length of the optical system including the first to sixth lensesis F, and TTL/F≤0.83.

The second lens and the third lens may be formed of plastic havingoptical characteristics different from each other.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating an example of a form in whicha multi-member optical imaging system in the examples described hereinis mounted in a portable electronic device.

FIG. 2 is a view illustrating a first example of a first optical imagingsystem.

FIG. 3 illustrates curves representing aberration characteristics of thefirst example of the first optical imaging system illustrated in FIG. 2.

FIG. 4 is a view illustrating a second example of a first opticalimaging system.

FIG. 5 illustrates curves representing aberration characteristics of thesecond example of the first optical imaging system illustrated in FIG.4.

FIG. 6 is a view illustrating a third example of a first optical imagingsystem in the examples described herein.

FIG. 7 illustrates curves representing aberration characteristics of thethird example of the first optical imaging system illustrated in FIG. 6.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be apparent after an understanding of thedisclosure of this application. For example, the sequences of operationsdescribed herein are merely examples, and are not limited to those setforth herein, but may be changed as will be apparent after anunderstanding of the disclosure of this application, with the exceptionof operations necessarily occurring in a certain order. Also,descriptions of features that are known in the art may be omitted forincreased clarity and conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided merelyto illustrate some of the many possible ways of implementing themethods, apparatuses, and/or systems described herein that will beapparent after an understanding of the disclosure of this application.

In the drawings, the thicknesses, sizes, and shapes of lenses have beenslightly exaggerated for convenience of explanation. Particularly, theshapes of spherical surfaces or aspherical surfaces illustrated in thedrawings are illustrated by way of example. That is, the shapes of thespherical surfaces or the aspherical surfaces are not limited to thoseillustrated in the drawings.

An aspect of the present disclosure may provide an optical imagingsystem which may be easily applied to a portable electronic device,readily perform an aberration correction, and have a narrow field ofview.

Referring to FIG. 1, a multi-member optical imaging system in theexamples described herein may include a plurality of optical imagingsystems and each of the plurality of optical imaging systems may includea plurality of lenses.

For example, the multi-member optical imaging system in the examplesdisclosed herein may include a first optical imaging system 400 and asecond imaging system 500.

The first optical imaging system 400 and the second optical imagingsystem 500 may have different fields of view. A field of view of thefirst optical imaging system 400 may be narrower than that of the secondoptical imaging system 500. As an example, the field of view of thefirst optical imaging system 400 may be smaller than 44°, and the fieldof view of the second optical imaging system 500 may be greater thanthat of the first optical imaging system 400.

As described above, a plurality of optical imaging systems may bedesigned to have different fields of view to thus capture an image of asubject at various depths and implement a zoom function.

In addition, since an image having a high level of resolution or abright image may be generated by using (for example, synthesizing) aplurality of images for one subject, an image of the subject may beclearly captured even in a low illuminance environment.

The plurality of optical imaging systems may be mounted in a portableelectronic device 600.

Examples of the first optical imaging system 400 will hereinafter bedescribed with reference to FIGS. 2 through 7.

The first optical imaging system 400 in the examples disclosed hereinmay include a plurality of lenses disposed along an optical axis. Theplurality of lenses may be disposed to be spaced apart from each otherby preset distances along the optical axis.

As an example, the first optical imaging system 400 may include sixlenses.

In the examples disclosed herein in which the optical imaging systemincludes six lenses, a first lens refers to a lens closest to an object,while a sixth lens refers to a lens closest to an image sensor.

In addition, a first surface of each lens refers to a surface thereofclosest to an object side (or an object-side surface) and a secondsurface of each lens refers to a surface thereof closest to an imageside (or an image-side surface). Further, in the present specification,all numerical values of radii of curvature, thicknesses, distances, andthe like, of lenses are indicated by millimeters (mm), and an angle isindicated by degrees.

Further, in a description for a shape of each of the lenses, the meaningthat one surface of a lens is convex is that a paraxial region portionof a corresponding surface is convex, and the meaning that one surfaceof a lens is concave is that a paraxial region portion of acorresponding surface is concave. Therefore, although it is describedthat one surface of a lens is convex, an edge portion of the lens may beconcave. Likewise, although it is described that one surface of a lensis concave, an edge portion of the lens may be convex.

A paraxial region refers to a narrow region in the vicinity of anoptical axis.

The first optical imaging system 400 in the examples disclosed hereinmay include six lenses.

For example, the first optical imaging system 400 in the examplesdisclosed herein may include a first lens, a second lens, a third lens,a fourth lens, a fifth lens, and a sixth lens sequentially disposed fromthe object side.

However, the first optical imaging system 400 in the examples disclosedherein is not limited to only including six lenses, but may furtherinclude other components.

For example, the first optical imaging system 400 may further include animage sensor configured to convert an image of a subject incident on theimage sensor into an electrical signal.

In addition, the first optical imaging system 400 may further include aninfrared cut-off filter configured to filter infrared light. Theinfrared cut-off filter may be disposed between a lens (as an example,the sixth lens) closest to the image sensor and the image sensor.

In addition, the first optical imaging system 400 may further include astop for controlling an amount of light. For example, the stop may bedisposed between the third lens and the fourth lens.

In the first optical imaging system 400 in the examples disclosedherein, all of the lenses may be formed of plastic. In addition, eachlens may be formed of plastic having optical characteristics differentfrom those of an adjacent lens.

In addition, the plurality of lenses may have at least one asphericalsurface.

That is, at least one of first and second surfaces of all of the firstto sixth lenses may be an aspherical surface. Here, the asphericalsurfaces of the first to sixth lenses may be represented by thefollowing Equation 1:

$\begin{matrix}{Z = {\frac{{cY}^{2}}{1 + \sqrt{1 - {\left( {1 + K} \right)c^{2}Y^{2}}}} + {AY}^{4} + {BY}^{6} + {CY}^{8} + {DY}^{10} + {EY}^{12} + {FY}^{14} + {GY}^{16} + \ldots}} & (1)\end{matrix}$

In Equation 1, c is a curvature (an inverse of a radius of curvature) ofa lens, K is a conic constant, and Y is a distance from a certain pointon an aspherical surface of the lens to an optical axis in a directionperpendicular to the optical axis. In addition, constants A to G areaspherical coefficients. In addition, Z is a distance between thecertain point on the aspherical surface of the lens at the distance Yand a tangential plane meeting the apex of the aspherical surface of thelens.

The first optical imaging system 400 including the first to sixth lensesmay have positive refractive power/negative refractive power/negativerefractive power/positive refractive power/negative refractivepower/positive refractive power sequentially from the object side.

Alternatively, the first optical imaging system 400 may have positiverefractive power/negative refractive power/negative refractivepower/negative refractive power/negative refractive power/positiverefractive power.

The first optical imaging system 400 in the examples disclosed hereinmay satisfy the following Conditional Expressions 2-7:

TTL/F≤0.83   (2)

2.2<D23/D34<5.4   (3)

10<D23/D12<22   (4)

58<D45/D56<65   (5)

0.3<f1/F<0.4   (6)

FOV<44°  (7)

In the above Conditional Expressions 2-7, TTL is a distance from anobject-side surface of the first lens to an imaging plane of the imagesensor, F is an overall focal length of the first optical imaging system400, D12 is an optical axis distance between the first lens and thesecond lens, D23 is an optical axis distance between the second lens andthe third lens, D34 is an optical axis distance between the third lensand the fourth lens, D45 is an optical axis distance between the fourthlens and the fifth lens, D56 is an optical axis distance between thefifth lens and the sixth lens, f1 is a focal length of the first lens,and FOV is a field of view of the first optical imaging system 400.

Next, the first to sixth lenses constituting the first optical imagingsystem 400 in the examples disclosed herein will be described.

The first lens may have positive refractive power.

In addition, both surfaces of the first lens may be convex. That is,first and second surfaces of the first lens may be convex.

At least one of the first and second surfaces of the first lens may bean aspherical surface. For example, both surfaces of the first lens maybe aspherical surfaces.

The second lens may have negative refractive power. In addition, thesecond lens may have a meniscus shape of which an object-side surface isconvex. That is, a first surface of the second lens may be convex, and asecond surface thereof may be concave. Alternatively, both surfaces ofthe second lens may be concave. That is, the first and second surfacesof the second lens may be concave.

At least one of the first and second surfaces of the second lens may bean aspherical surface. For example, both surfaces of the second lens maybe aspherical surfaces.

In addition, the first lens and the second lens may be formed of plastichaving different optical characteristics from each other. That is, thefirst lens may be formed of plastic having first optical characteristicsand the second lens may be formed of plastic having second opticalcharacteristics different from the first optical characteristics.

The third lens may have negative refractive power. In addition, thethird lens may have a meniscus shape of which an object-side surface isconvex. That is, a first surface of the third lens may be convex, and asecond surface thereof may be concave.

At least one of the first and second surfaces of the third lens may bean aspherical surface. For example, both surfaces of the third lens maybe aspherical surfaces.

The fourth lens may have positive or negative refractive power. Inaddition, the fourth lens may have a meniscus shape of which anobject-side surface is convex. That is, a first surface of the fourthlens may be convex, and a second surface thereof may be concave.

At least one of the first and second surfaces of the fourth lens may bean aspherical surface. For example, both surfaces of the fourth lens maybe aspherical surfaces.

In addition, at least one inflection point may be formed on the firstsurface of the fourth lens. For example, the first surface of the fourthlens may be convex in the paraxial region and become concave toward anedge thereof.

In addition, the third lens and the fourth lens may be formed of plastichaving different optical characteristics from each other.

Further, a stop may be disposed between the third lens and the fourthlens.

The fifth lens may have negative refractive power. In addition, thefifth lens may have a meniscus shape of which an image-side surface isconvex. That is, a first surface of the fifth lens may be concave, and asecond surface thereof may be convex.

At least one of the first and second surfaces of the fifth lens may bean aspherical surface. For example, both surfaces of the fifth lens maybe aspherical surfaces.

In addition, at least one inflection point may be formed on the firstsurface of the fifth lens. For example, the first surface of the fifthlens may be concave in the paraxial region and become convex toward anedge thereof.

The sixth lens may have positive refractive power. In addition, thesixth lens may have a meniscus shape of which an image-side surface isconvex. That is, a first surface of the fifth lens may be concave, and asecond surface thereof may be convex.

At least one of the first and second surfaces of the sixth lens may bean aspherical surface. For example, both surfaces of the sixth lens maybe aspherical surfaces.

In addition, the fifth lens and the sixth lens may be formed of plastichaving different optical characteristics.

In the first optical imaging system 400 configured as described above, aplurality of lenses may perform an aberration correction function toincrease aberration improvement performance.

As an example, an optical axis distance between the first lens and thesecond lens formed of the plastic having different opticalcharacteristics may be configured to be relatively short to improvechromatic aberration correction performance. That is, the first andsecond lenses may be disposed along the optical axis relatively close toeach other.

In addition, an optical axis distance between the third lens and thefourth lens formed of the plastic having different opticalcharacteristics may be configured to be relatively short, to improvechromatic aberration correction performance. That is, the third andfourth lenses may be disposed along the optical axis relatively close toeach other.

In addition, an optical axis distance between the fifth lens and thesixth lens formed of the plastic having different opticalcharacteristics may be configured to be relatively short to improvechromatic aberration correction performance. That is, the fifth andsixth lenses may be disposed along the optical axis relatively close toeach other.

Meanwhile, the first optical imaging system 400 in the examplesdisclosed herein may have characteristics of a telephoto lens of which afield of view is less than 44°.

A first example of the optical imaging system 400 in the examplesdisclosed herein will be described with reference to FIGS. 2 and 3.

The first optical imaging system 400 a in the examples disclosed hereinmay include an optical system including a first lens 110, a second lens120, a third lens 130, a fourth lens 140, a fifth lens 150, and a sixthlens 160, and may further include an infrared cut-off filter 170, animage sensor 180, and a stop ST.

Here, example lens characteristics (radii of curvature, thicknesses oflenses or distances between the lenses, refractive indices, Abbenumbers, and effective aperture radii) of each lens are represented inTable 1.

TABLE 1 Radius of Thickness or Refractive Abbe Effective Focal Example 1Curvature Distance Index Number Aperture Radius Length S1 1.4639467310.964935043 1.536 55.650 1.220 2.416 S2 −8.646866285 0.025 1.097 S3959.5448645 0.24 1.667 20.353 1.042 −5.09 S4 3.382933555 0.5291616760.899 S5 19.42810857 0.24 1.546 56.114 0.708 −4.382 S6 2.1209266830.098220106 0.617 S7 5.182858293 0.304685087 1.667 20.353 0.608 71.91 S85.674158832 1.45629814 0.744 S9 −2.264152779 0.4 1.536 55.650 1.822−5.153 S10 −13.32304852 0.025 1.928 S11 −21.29550925 0.611699948 1.66720.353 2.090 7.756 S12 −4.210032884 0.025 2.204 S13 Infinity 0.21 1.51864.197 2.400 S14 Infinity 0.670179044 2.451 Image Infinity −0.05 2.725

Meanwhile, in the first example, an overall focal length F of the firstoptical imaging system 400 a is 6.927 mm, a focal length f1 of the firstlens 110 is 2.416 mm, a focal length f2 of the second lens 120 is −5.09mm, a focal length f3 of the third lens 130 is −4.382 mm, a focal lengthf4 of the fourth lens 140 is 71.91 mm, a focal length f5 of the fifthlens 150 is −5.153 mm, and a focal length f6 of the sixth lens 160 is7.756 mm.

In the first example, field of view (FOV) of the first optical imagingsystem 400 a is 43.43° and the effective aperture radius (earl) of anobject-side surface of the first lens 110 is 1.22 mm.

Meanwhile, the effective aperture radius refers to a radius of a surface(an object-side surface or an image-side surface) of each lens throughwhich light actually passes. As an example, referring to FIG. 1, theeffective aperture radius (earl) refers to a straight line distancebetween an end portion at which light is incident on the object-sidesurface of the first lens 110 and the optical axis.

In the first example, the first lens 110 may have positive refractivepower, and a first surface and a second surface thereof may be convex ina paraxial region.

The second lens 120 may have negative refractive power, and a firstsurface thereof may be convex in a paraxial region and a second surfacethereof may be concave in the paraxial region.

An optical axis distance between the first lens 110 and the second lens120 may be configured to be relatively short. That is, the first andsecond lenses 110, 120 may be disposed along the optical axis relativelyclose to each other.

The first lens 110 and the second lens 120 may be formed of plastichaving optical characteristics different from each other. For example,the Abbe numbers of the first lens 110 and the second lens 120 may bedifferent from each other.

The optical axis distance between the first lens 110 and the second lens120 formed of the plastic having different optical characteristics maybe configured to be relatively short to improve chromatic aberrationcorrection performance.

The third lens 130 may have negative refractive power, and a firstsurface thereof may be convex in the paraxial region and a secondsurface thereof may be concave in the paraxial region.

The fourth lens 140 may have positive refractive power, and a firstsurface thereof may be convex in a paraxial region and a second surfacethereof may be concave in the paraxial region.

An optical axis distance between the third lens 130 and the fourth lens140 may be configured to be relatively short. That is, the third andfourth lenses 130, 140 may be disposed along the optical axis relativelyclose to each other.

The third lens 130 and the fourth lens 140 may be formed of plastichaving optical characteristics different from each other. For example,the Abbe numbers of the third lens 130 and the fourth lens 140 may bedifferent from each other.

The optical axis distance between the third lens 130 and the fourth lens140 formed of the plastic having different optical characteristics maybe configured to be relatively short to improve chromatic aberrationcorrection performance.

In addition, at least one inflection point may be formed on the firstsurface of the fourth lens 140. For example, the first surface of thefourth lens 140 may be convex in a paraxial region and become concavetoward an edge thereof.

In addition, the stop ST may be disposed between the third lens 130 andthe fourth lens 140.

The inflection point may be formed on the surface of the lens disposedclose to the stop ST to thus improve correction performance ofastigmatism and coma-aberration.

The fifth lens 150 may have negative refractive power, and a firstsurface thereof may be concave in the paraxial region and a secondsurface thereof may be convex in the paraxial region.

In addition, at least one inflection point may be formed on the firstsurface of the fifth lens 150. For example, the first surface of thefifth lens 150 may be concave in a paraxial region and become convextoward an edge thereof.

The sixth lens 160 may have positive refractive power, and a firstsurface thereof may be concave in the paraxial region and a secondsurface thereof may be convex in the paraxial region.

An optical axis distance between the fifth lens 150 and the sixth lens160 may be configured to be relatively short. That is, the fifth andsixth lenses 150, 160 may be disposed along the optical axis relativelyclose to each other.

The fifth lens 150 and the sixth lens 160 may be formed of plastichaving optical characteristics different from each other. For example,the Abbe numbers of the fifth lens 150 and the sixth lens 160 may bedifferent from each other.

The optical axis distance between the fifth lens 150 and the sixth lens160 formed of the plastic having different optical characteristics maybe configured to be relatively short to improve chromatic aberrationcorrection performance.

Meanwhile, respective surfaces of the first to sixth lenses 110 to 160may have aspherical coefficients as illustrated in Table. 2. Forexample, all of object-side surfaces and image-side surfaces of thefirst to sixth lenses 110 to 160 may be aspherical surfaces.

TABLE 2 S1 S2 S3 S4 S5 S6 R  1.463946731 −8.646866285  959.54486453.382933555 19.42810857  2.120926683 K −0.133989384 0.9983442460.297909075 0.509997595 −6.685547374  0.87805276 A 1.09E−24 0.0288637780.020509933 0.019630518 0.055022581 −0.02306423 B −4.27E−36   7.08E−05−0.00300168 0.038792531 −0.287790834 −1.37E−01 C 1.00E−47 −1.24E−030.007410129 −0.198724478 0.693412766  2.50E−01 D −1.35E−59   2.47E−04−0.004790544 0.435476904 −1.004707565 −1.49E−01 E 1.03E−71 −2.28E−050.001506562 −0.491780491 0.693934244  4.23E−02 F −4.13E−84   1.05E−06−0.000285241 0.268401617 −0.219209737 −5.89E−03 G 6.79E−97 −1.92E−082.37E−05 −0.053983113 0.026051365  3.24E−04 S7 S8 S9 S10 S11 S12 R5.182858293 5.674158832 −2.264152779 −13.32304852 −21.29550925−4.210032884 K 0.999999858 4.73488621  −11.96617843 −27.08377426 97.99999914 −4.588713472 A −0.09512504 −1.05E−19 −0.166954516−0.097017719 −7.30E−17 −1.78E−45  B −0.09512505  2.44E−30 0.1126229880.035075267  5.98E−24 2.94E−67 C 0.050439683 −3.58E−41 −0.028457272−0.008279172 −1.98E−31 −1.33E−89  D −0.067098204  3.27E−52 0.0025530830.001145081  2.98E−39  3.14E−112 E 0.060515193 −1.81E−63 0.00021226−8.67E−05 −2.07E−47 −4.00E−135 F −0.021416941  5.54E−75 −5.37E−05 3.28E−06  6.58E−56  2.59E−158 G 0.002587362 −7.14E−87  2.60E−06−4.84E−08 −7.79E−65 −6.67E−182

In addition, the first optical imaging system 400 a configured asdescribed above may have aberration characteristics illustrated in FIG.3.

A second example of the first optical imaging system 400 will bedescribed with reference to FIGS. 4 and 5.

The second example of the first optical imaging system 400 b may includean optical system including a first lens 210, a second lens 220, a thirdlens 230, a fourth lens 240, a fifth lens 250, and a sixth lens 260, andmay further include an infrared cut-off filter 270, an image sensor 280,and a stop ST.

Here, lens characteristics (radii of curvature, thicknesses of lenses ordistances between the lenses, refractive indices, Abbe numbers, andeffective aperture radii) of each lens are represented in Table 3.

TABLE 3 Radius of Thickness or Refractive Abbe Effective Focal Example 2Curvature Distance Index Number Aperture Radius Length S1 1.4503246720.936653477 1.536 55.650 1.200 2.458986 S2 −11.2040274 0.027023495 1.073S3 −16.33022207 0.22 1.667 20.353 1.046 −4.98814 S4 4.2003159130.437131956 0.924 S5 2.075211629 0.22 1.536 55.650 0.730 −6.26754 S61.235379194 0.15 0.637 S7 4.957874783 0.22 1.667 20.353 0.623 −34.5267S8 4.007088066 1.617148606 0.713 S9 −2.426080348 0.4 1.536 55.650 1.867−5.20057 S10 −19.77431236 0.025 1.957 S11 −21.28181615 0.642042465 1.66720.353 2.109 8.214169 S12 −4.409332441 0.025 2.229 S13 Infinity 2.10E−011.518 64.197 2.432 S14 Infinity 6.39E−01 2.482 Image Infinity −1.89E−02 2.725

Meanwhile, an overall focal length F of the second example of the firstoptical imaging system 400 b is 6.9262 mm, a focal length f1 of thefirst lens 210 is 2.458986 mm, a focal length f2 of the second lens 220is −4.98814 mm, a focal length f3 of the third lens 230 is −6.26754 mm,a focal length f4 of the fourth lens 240 is −34.5267 mm, a focal lengthf5 of the fifth lens 250 is −5.20057 mm, and a focal length f6 of thesixth lens 260 is 8.214169 mm.

In addition, a field of view (FOV) of the second example of the firstoptical imaging system 400 b is 43.7°.

In the second example, the first lens 210 may have positive refractivepower, and a first surface and a second surface thereof may be convex inthe paraxial region.

The second lens 220 may have negative refractive power, and a firstsurface and a second surface thereof may be concave in the paraxialregion.

An optical axis distance between the first lens 210 and the second lens220 may be configured to be relatively short. That is, the first andsecond lenses 210, 220 may be disposed along the optical axis relativelyclose to each other.

The first lens 210 and the second lens 220 may be formed of plastichaving optical characteristics different from each other. For example,the Abbe numbers of the first lens 210 and the second lens 220 may bedifferent from each other.

The optical axis distance between the first lens 210 and the second lens220 formed of the plastic having different optical characteristics maybe configured to be relatively short to improve chromatic aberrationcorrection performance.

The third lens 230 may have negative refractive power, and a firstsurface thereof may be convex in the paraxial region and a secondsurface thereof may be concave in the paraxial region.

The fourth lens 240 may have negative refractive power, and a firstsurface thereof may be convex in the paraxial region and a secondsurface thereof may be concave in the paraxial region.

An optical axis distance between the third lens 230 and the fourth lens240 may be configured to be relatively short. That is, the third andfourth lenses 230, 240 may be disposed along the optical axis relativelyclose to each other.

The third lens 230 and the fourth lens 240 may be formed of plastichaving optical characteristics different from each other. For example,the Abbe numbers of the third lens 230 and the fourth lens 240 may bedifferent from each other.

The optical axis distance between the third lens 230 and the fourth lens240 formed of the plastic having different optical characteristics maybe configured to be relatively short to improve chromatic aberrationcorrection performance.

In addition, at least one inflection point may be formed on the firstsurface of the fourth lens 240. For example, the first surface of thefourth lens 240 may be convex in a paraxial region and become concavetoward an edge thereof.

In addition, the stop ST may be disposed between the third lens 230 andthe fourth lens 240.

The inflection point may be formed on the surface of the lens disposedclose to the stop ST to improve correction performance of astigmatismand coma-aberration.

The fifth lens 250 may have negative refractive power, and a firstsurface thereof may be concave in the paraxial region and a secondsurface thereof may be convex in the paraxial region.

In addition, at least one inflection point may be formed on the firstsurface of the fifth lens 250. For example, the first surface of thefifth lens 250 may be concave in a paraxial region and become convextoward an edge thereof.

The sixth lens 260 may have positive refractive power, and a firstsurface thereof may be concave in the paraxial region and a secondsurface thereof may be convex in the paraxial region.

An optical axis distance between the fifth lens 250 and the sixth lens260 may be configured to be relatively short. That is, the fifth andsixth lenses 250, 260 may be disposed along the optical axis relativelyclose to each other.

The fifth lens 250 and the sixth lens 260 may be formed of plastichaving optical characteristics different from each other. For example,the Abbe numbers of the fifth lens 250 and the sixth lens 260 may bedifferent from each other.

The optical axis distance between the fifth lens 250 and the sixth lens260 formed of the plastic having different optical characteristics maybe configured to be relatively short to improve chromatic aberrationcorrection performance.

Meanwhile, respective surfaces of the first to sixth lenses 210 to 260may have aspherical coefficients as illustrated in Table. 4. Forexample, all of object-side surfaces and image-side surfaces of thefirst to sixth lenses 210 to 260 may be aspherical surfaces.

TABLE 4 S1 S2 S3 S4 S5 S6 R  1.450324672 −11.2040274   −16.330222074.200315913 2.075211629 1.235379194 K −0.108999286 0.9988035480.473432126 −0.139419309 −6.777058665 0.138963086 A 1.09E−24 0.0372392080.024067335 −0.022840984 −0.225509683 −0.44649055 B −4.27E−36   5.04E−050.027295735 0.090583232 0.218639087 0.305701589 C 1.00E−47 −1.97E−03−0.019630308 −0.158336648 0.085773811 0.025122088 D −1.35E−59   4.29E−040.00519754 0.2541712 −0.452361137 −0.098661713 E 1.03E−71 −4.23E−05−0.000306514 −0.267349847 0.369830363 0.040930784 F −4.13E−84   2.03E−06−0.000158039 0.136893052 −0.121185635 −0.00708053 G 6.79E−97 −3.86E−082.52E−05 −0.025106993 0.014485107 0.000462094 S7 S8 S9 S10 S11 S12 R4.957874783 4.007088066 −2.426080348 −19.77431236 −21.28181615−4.409332441 K 0.999999924 4.703740249 −21.30984089 −27.08259006 97.75024463 −2.410568354 A −0.118452535 −1.05E−19 −0.246764617−0.133021884 −7.30E−17 −1.78E−45  B −0.147871334  2.44E−30 0.1783137370.05325333  5.98E−24 2.94E−67 C 0.316026392 −3.58E−41 −0.059061686−0.012231444 −1.98E−31 −1.33E−89  D −0.327626633  3.27E−52 0.0113610760.001589243  2.98E−39  3.14E−112 E 0.169384846 −1.81E−63 −0.00127409−1.11E−04 −2.07E−47 −4.00E−135 F −0.041821082  5.54E−75  7.68E−05 3.90E−06  6.58E−56  2.59E−158 G 0.003941456 −7.14E−87 −1.93E−06−5.34E−08 −7.79E−65 −6.67E−182

In addition, the second example of the first optical imaging system 400b configured as described above may have aberration characteristicsillustrated in FIG. 5.

A third example of the first optical imaging system 400 will bedescribed with reference to FIGS. 6 and 7.

The third example of the first optical imaging system 400 c may includean optical system including a first lens 310, a second lens 320, a thirdlens 330, a fourth lens 340, a fifth lens 350, and a sixth lens 360, andmay further include an infrared cut-off filter 370, an image sensor 380,and a stop ST.

Here, lens characteristics (radii of curvature, thicknesses of lenses ordistances between the lenses, refractive indices, Abbe numbers, andeffective aperture radii) of each lens are represented in Table 5.

TABLE 5 Radius of Thickness or Refractive Abbe Effective Focal Example 3Curvature Distance Index Number Aperture Radius Length S1 1.4275929750.947667138 1.536 55.650 1.200 2.616186 S2 −61.10520147 0.025 1.049 S378.59688111 0.22 1.667 20.353 1.026 −5.39922 S4 3.439272796 0.2595924860.902 S5 2.166641666 0.22 1.536 55.650 0.791 −7.62391 S6 1.3657898420.113236642 0.699 S7 3.138329321 0.22 1.667 20.353 0.686 −43.1324 S82.750259986 1.830059953 0.760 S9 −2.444344097 0.4 1.536 55.650 1.892−5.16861 S10 −21.93963443 0.030039535 2.007 S11 −21.36820118 0.6294042451.667 20.353 2.143 9.398628 S12 −4.90361342 0.025 2.261 S13 Infinity0.21 1.518 64.197 2.454 S14 Infinity 0.65661826 2.502 Image Infinity−0.036138976 2.726

Meanwhile, an overall focal length F of the third example of the firstoptical imaging system 400 c is 6.927 mm, a focal length f1 of the firstlens 310 is 2.616186 mm, a focal length f2 of the second lens 320 is−5.39922 mm, a focal length f3 of the third lens 330 is −7.62391 mm, afocal length f4 of the fourth lens 340 is −43.1324 mm, a focal length f5of the fifth lens 350 is −5.16861 mm, and a focal length f6 of the sixthlens 360 is 9.398628 mm.

In addition, in the third example, a field of view (FOV) of the firstoptical imaging system 400 c is 43.77°.

In the third example, the first lens 310 may have positive refractivepower, and a first surface and a second surface thereof may be convex inthe paraxial region.

The second lens 320 may have negative refractive power, and a firstsurface thereof may be convex in the paraxial region and a secondsurface thereof may be concave in the paraxial region.

An optical axis distance between the first lens 310 and the second lens320 may be configured to be relatively short. That is, the first andsecond lenses 310, 320 may be disposed along the optical axis relativelyclose to each other.

The first lens 310 and the second lens 320 may be formed of plastichaving optical characteristics different from each other. For example,the Abbe numbers of the first lens 310 and the second lens 320 may bedifferent from each other.

The optical axis distance between the first lens 310 and the second lens320 each formed of plastic having different optical characteristics maybe configured so that the first lens 310 and the second lens 320 arerelatively close to each other to improve chromatic aberrationcorrection performance.

The third lens 330 may have negative refractive power, and a firstsurface thereof may be convex in the paraxial region and a secondsurface thereof may be concave in the paraxial region.

The fourth lens 340 may have positive refractive power, and a firstsurface thereof may be convex in the paraxial region and a secondsurface thereof may be concave in the paraxial region.

An optical axis distance between the third lens 330 and the fourth lens340 may be configured to be relatively short. That is, the third andfourth lenses 330, 340 may be disposed along the optical axis relativelyclose to each other.

The third lens 330 and the fourth lens 340 may be formed of plastichaving optical characteristics different from each other. For example,the Abbe numbers of the third lens 330 and the fourth lens 340 may bedifferent from each other.

The optical axis distance between the third lens 330 and the fourth lens340 each formed of plastic having different optical characteristics maybe configured so that the third lens 330 and the fourth lens 340 arerelatively close to each other to improve chromatic aberrationcorrection performance.

In addition, at least one inflection point may be formed on the firstsurface of the fourth lens 340. For example, the first surface of thefourth lens 340 may be convex in a paraxial region and become concavetoward an edge thereof.

In addition, the stop ST may be disposed between the third lens 330 andthe fourth lens 340.

The inflection point may be formed on the surface of the lens disposedclose to the stop ST to improve correction performance of astigmatismand coma-aberration.

The fifth lens 350 may have negative refractive power, and a firstsurface thereof may be concave in the paraxial region and a secondsurface thereof may be convex in the paraxial region.

In addition, at least one inflection point may be formed on the firstsurface of the fifth lens 350. For example, the first surface of thefifth lens 350 may be concave in the paraxial region and become convextoward an edge thereof.

The sixth lens 360 may have positive refractive power, and a firstsurface thereof may be concave in the paraxial region and a secondsurface thereof may be convex in the paraxial region.

An optical axis distance between the fifth lens 350 and the sixth lens360 may be configured to be relatively short. That is, the fifth andsixth lenses 350, 360 may be disposed along the optical axis relativelyclose to each other.

The fifth lens 350 and the sixth lens 360 may be formed of plastichaving optical characteristics different from each other. For example,the Abbe numbers of the fifth lens 350 and the sixth lens 360 may bedifferent from each other.

The optical axis distance between the fifth lens 350 and the sixth lens360 each formed of plastic having different optical characteristics maybe configured so that the fifth lens 350 and the sixth lens 360 arerelatively close to each other to improve chromatic aberrationcorrection performance.

Meanwhile, respective surfaces of the first to sixth lenses 310 to 360may have aspherical coefficients as illustrated in Table. 6. Forexample, all of object-side surfaces and image-side surfaces of thefirst to sixth lenses 310 to 360 may be aspherical surfaces.

TABLE 6 S1 S2 S3 S4 S5 S6 R  1.427592975 −61.10520147   78.596881113.439272796 2.166641666 1.365789842 K −0.047546604 0.9994733190.473358657 −0.093875344 −5.48212518 0.079998285 A 1.09E−24 0.0426687460.02395669 −0.041645551 −0.241683076 −0.505530899 B −4.27E−36   4.67E−030.030560199 0.154967881 0.248415228 0.369625906 C 1.00E−47 −4.32E−030.002098445 −0.327888285 0.27714106 −0.016926512 D −1.35E−59   8.92E−04−0.019122208 0.715450376 −0.804521888 −0.081095321 E 1.03E−71 −8.81E−050.00977612 −0.877981674 0.606501119 0.036390072 F −4.13E−84   4.31E−06−0.002052284 0.486435606 −0.192494979 −0.006425488 G 6.79E−97 −8.33E−081.61E−04 −0.096621787 0.022583034 0.000422322 S7 S8 S9 S10 S11 S12 R3.138329321 2.750259986 −2.444344097 −21.93963443 −21.36820118−4.90361342  K 1 3.233332688 −22.60105043 −27.08259006  95.75590308−1.256217694 A −0.186840269 −1.05E−19 −0.238409484 −0.122004598−7.30E−17 −1.78E−45  B −0.143659011  2.44E−30 0.160415986 0.047044938 5.98E−24 2.94E−67 C 0.338475555 −3.58E−41 −0.051848079 −0.009867783−1.98E−31 −1.33E−89  D −0.372713191  3.27E−52 0.010294009 0.001102409 2.98E−39  3.14E−112 E 0.207680172 −1.81E−63 −0.001247111 −6.58E−05−2.07E−47 −4.00E−135 F −0.055388846  5.54E−75  8.30E−05  1.98E−06 6.58E−56  2.59E−158 G 0.005629237 −7.14E−87 −2.30E−06 −2.36E−08−7.79E−65 −6.67E−182

In addition, the third example of the first optical imaging system 400 cconfigured as described above may have aberration characteristicsillustrated in FIG. 7.

Table 7 summarizes some of the optical characteristics of the firstexample of the first optical imaging system 400 a, the second example ofthe first optical imaging system 400 b, and the third example of thefirst optical imaging system 400 c described above.

TABLE 7 Example 1 Example 2 Example 3 TTL 5.75 5.7497 5.75 F 6.9276.9262 6.927 FOV 43.43 43.696 43.7667 TTL/F 0.830 0.830 0.830 D23/D345.388 2.914 2.292 f1/F 0.349 0.355 0.378

In the examples described herein, the optical imaging system whichreadily performs an aberration correction and has a narrow field of viewmay be easily applied to a portable electronic device.

While this disclosure includes specific examples, it will be apparentafter an understanding of the disclosure of this application thatvarious changes in form and details may be made in these exampleswithout departing from the spirit and scope of the claims and theirequivalents. The examples described herein are to be considered in adescriptive sense only, and not for purposes of limitation. Descriptionsof features or aspects in each example are to be considered as beingapplicable to similar features or aspects in other examples. Suitableresults may be achieved if the described techniques are performed in adifferent order, and/or if components in a described system,architecture, device, or circuit are combined in a different manner,and/or replaced or supplemented by other components or theirequivalents. Therefore, the scope of the disclosure is defined not bythe detailed description, but by the claims and their equivalents, andall variations within the scope of the claims and their equivalents areto be construed as being included in the disclosure.

What is claimed is:
 1. An optical imaging system comprising: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens sequentially disposed on an optical axis from an object side toward an image side, wherein a distance from an object-side surface of the first lens to an imaging plane of an image sensor is TTL, an overall focal length of an optical system including the first to sixth lenses is F, and TTL/F≤0.83, and wherein an optical axis distance between the second lens and the third lens is D23, an optical axis distance between the third lens and the fourth lens is D34, and 2.2<D23/D34<5.4.
 2. The optical imaging system of claim 1, wherein a field of view of the optical system including the first to sixth lenses is FOV and FOV 44°.
 3. The optical imaging system of claim 1, wherein a focal length of the first lens is f1 and 0.3<f1/F<0.4.
 4. The optical imaging system of claim 1, wherein an optical axis distance between the first lens and the second lens is D12 and 10<D23/D12<22.
 5. The optical imaging system of claim 1, wherein an optical axis distance between the fourth lens and the fifth lens is D45, an optical axis distance between the fifth lens and the sixth lens is D56, and 58<D45/D56<65.
 6. The optical imaging system of claim 1, wherein the first lens comprises positive refractive power, and among absolute values of focal lengths of the first to sixth lenses, the absolute value of the focal length of the first lens is the shortest.
 7. The optical imaging system of claim 1, wherein the second lens comprises negative refractive power and an image-side surface thereof is concave.
 8. The optical imaging system of claim 1, wherein the third lens comprises negative refractive power, an object-side surface thereof is convex, and an image-side surface thereof is concave.
 9. The optical imaging system of claim 1, wherein the fourth lens comprises positive or negative refractive power, an object-side surface thereof is convex, and an image-side surface thereof is concave.
 10. The optical imaging system of claim 1, wherein the fifth lens comprises negative refractive power, an object-side surface thereof is concave, and an image-side surface thereof is convex.
 11. The optical imaging system of claim 1, wherein the sixth lens comprises positive refractive power, an object-side surface thereof is concave, and an image-side surface thereof is convex.
 12. The optical imaging system of claim 1, wherein the first to sixth lenses are each formed of plastic comprising optical characteristics different from an adjacent lens.
 13. The optical imaging system of claim 1, further comprising a stop disposed between the third lens and the fourth lens.
 14. The optical imaging system of claim 1, wherein at least one inflection point is formed on an object-side surface of the fourth lens.
 15. A multi-member optical imaging system comprising: a first optical imaging system comprising: a first field of view, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens sequentially disposed on an optical axis from an object side toward an image side, wherein a distance from an object-side surface of the first lens to an imaging plane of an image sensor is TTL, an overall focal length of an optical system including the first to sixth lenses is F, and TTL/F≤0.83; and a second optical imaging system comprising a second field of view different from the first field of view.
 16. The multi-member optical imaging system of claim 15, wherein an optical axis distance between the second lens and the third lens is D23, an optical axis distance between the third lens and the fourth lens is D34, and 2.2<D23/D34<5.4, and wherein the second lens and the third lens are formed of plastic having optical characteristics different from each other. 